package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisData;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;

import java.time.LocalDateTime;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 * 服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private CacheClient cacheClient;

    @Override
    public Result queryById(Long id) throws InterruptedException {
        //解决缓存穿透
        //Shop shop1 = queryWithPassThrough(id);
        Shop shop1 = cacheClient.queryWithPassThrough(
                CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);

        //互斥锁解决缓存击穿
        //Shop shop2 = queryWithMutex(id);

        //逻辑过期解决缓存击穿
        //Shop shop3 = queryWithLogicalExpire(id);
        Shop shop = cacheClient.queryWithLogicalExpire(
                CACHE_SHOP_KEY, id, Shop.class, this::getById, 20L, TimeUnit.SECONDS);




        if (shop == null) {
            return Result.fail("店铺不存在");
        }
        return Result.ok(shop);
    }


/*    //新建线程池
    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);*/

    /*public Shop queryWithLogicalExpire(Long id) {
        //从redis中查询商铺缓存
        String key = CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //判断是否存在
        if (StrUtil.isBlank(shopJson)) {
            //redis不存在，返回null
            return null;
        }
        //命中，需要先把json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        Shop shop = JSONUtil.toBean((JSONObject) redisData.getData(), Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        //判断是否过期
        if (expireTime.isAfter(LocalDateTime.now())) {
            //未过期，直接返回店铺信息
            return shop;
        }
        //已过期，需要redis缓存重建
        //获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        boolean isLock = tryLock(lockKey);
        //判断获取互斥锁成功与否
        if (isLock) {
            //成功，开启独立线程，实现缓存重建
            CACHE_REBUILD_EXECUTOR.submit(() -> {
                try {
                    //重建缓存
                    this.savaShop2Redis(id, 20L);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    //释放锁
                    unlock(lockKey);
                }
            });
        }
        //失败，返回过期的商铺信息
        return shop;
    }*/

/*    private boolean tryLock(String key) {
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    private void unlock(String key) {
        stringRedisTemplate.delete(key);
    }*/

    /*public Shop queryWithMutex(Long id) throws InterruptedException {
        //1 从redis中查询商铺缓存
        String key = CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2 判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            //存在，直接返回
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        //3 还有两种可能：空串和null（不存在）
        if (shopJson != null) {
            //空串，数据不存在
            return null;
        }
        //4 redis中不存在，实现redis缓存重建
        //4.1 获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        Shop shop = null;
        try {
            boolean isLock = tryLock(lockKey);
            //4.2 判断是否获取成功
            if (!isLock) {
                //4.3 失败 则休眠重试
                Thread.sleep(50);
                return queryWithMutex(id);
            }
            //4.4成功，根据id查询数据库
            shop = getById(id);
            //模拟数据库查询耗时操作
            Thread.sleep(500);

            //5 数据库中不存在，在redis中写入空串
            if (shop == null) {
                stringRedisTemplate.opsForValue().set(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
                return null;
            }
            //6 数据库中存在，写入redis
            stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        } finally {
            //7 释放锁
            unlock(lockKey);
        }
        return shop;
    }*/

/*    public Shop queryWithPassThrough(Long id) {
        //从redis中查询商铺缓存
        String key = CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            //存在，直接返回
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        //还有两种可能：空串和null（不存在）
        if (shopJson != null) {
            //空串，数据不存在
            return null;
        }
        //不存在，根据id查询数据库
        Shop shop = getById(id);
        //数据库中不存在，在redis中写入空串
        if (shop == null) {
            stringRedisTemplate.opsForValue().set(key, "", CACHE_NULL_TTL, TimeUnit.MINUTES);
            return null;
        }
        //数据库中存在，写入redis
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop), CACHE_SHOP_TTL, TimeUnit.MINUTES);
        return shop;
    }*/

    public void savaShop2Redis(Long id, Long expireSeconds) {
        //在数据库查询
        Shop shop = getById(id);
        //封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        //写入Redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(redisData));


    }


    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id = shop.getId();
        if (id == null) {
            return Result.fail("店铺id不能为空");
        }
        //更新数据库
        updateById(shop);
        //删除redis缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + id);
        return Result.ok();
    }
}
